The installation of pipe in underground service is accomplished by various methods. These methods include digging a trench mechanically or manually digging using a shovel. After a trench is dug, the pipe is usually pulled underground by means of a chinese finger trap. A chinese finger trap is a hollow wire mesh tube which encircles and grips the outside of the pipe. One end of the chinese finger trap is then attached to a motive device or pulling vehicle. The attachment on the motive device or pulling vehicle usually includes a shank or ripper which precedes the chinese finger trap in the earth. A ripper opens a trench in the earth within which the chinese finger trap pulls the pipe. Once installation is completed the chinese finger trap is then removed from the end of the pipe.
Removal of the chinese finger trap from the pipe can be difficult since the pipe is usually in the trench covered with earth. The chinese finger trap must be forcibly compressed to cause it to loosen its grip on the pipe. This manual maneuver is difficult when the mesh is compacted with soil. Further, the end of the pipe may be damaged during pulling. Finally, the nature of the chinese finger trap requires the tool to be under tension to perform as desired. The chinese finger trap cannot be used to “back” pipe into tight areas where the motive device cannot be operated.
The inventor is aware of a system in which a pipe is pulled by a plow or a tractor. Typically, a powered vehicle such as a tractor pulls a subsoil plow through the soil. Attached to the back of the plow and following in the path of the opening formed by the plow is a pipe puller that holds the end of the pipe. As the plow moves through the soil it pulls the pipe puller and the pipe into the opening formed by the plow.
One of the problems with pulling plastic pipe as opposed to pulling metal pipes is that the plastic pipe generally has an inherent resiliency that may cause the pipe puller to slip off the plastic pipe. Also the interior and exterior of plastic pipes tend to be smoother and more difficult to grasp than certain metal pipes. Another difficulty with plastic pipes is that they are usually relatively soft and may contain plasticizers that make the surface of the pipe difficult to firmly grasp. In addition some of the pipe pullers are difficult to “set” or quickly attach the pipe puller to the plastic pipe. The present invention eliminates the problem of slippage and also permits the user to quickly engage or disengage the pipe puller from the plastic pipe.
There remains a need for a pipe pulling method and device which allows the puller to be quickly and non-destructively detached from the pipe after pulling; protects the end of the pipe during the underground pulling operation; and allows the pipe to be pulled without damaging the pipe.
Furthermore, with regard to underground watering systems, it is desirable to have some means and method to pull at one time a plurality of pipes as through a slit trench in installing a watering system with said plurality of pipes, which are generally of a relatively small diameter, running to a common supply source. Plastic pipes are commonly used for such purpose and care must be exercised in the use of a pipe pulling device in connection with plastic pipes to avoid deforming or rupturing such pipes.
Therefore, there is a need for a pipe pulling device and method that can pull more than one pipe at once and which can safely pull more than one plastic pipe.